The report is intended as a public wake-up call regarding the danger of one in nine bridges across the U.S. today. The effort is part of T4’s mission to bring attention to national, state and local transportation policies.

11.5% Called Deficient

“Despite billions of dollars in annual federal, state and local funds directed toward the maintenance of existing bridges, 69,223 bridges — representing more than 11% of total highway bridges in the U.S. — are classified as ‘structurally deficient,’ according to the Federal Highway Administration (FHWA),” T4’s national report says.

While the average age of an American bridge is 42 years, nearly one-third of the nation’s highway bridges were at least 50 years old by the end of the last decade—a rate that will double by 2030 without substantial bridge replacement, T4 reports.

Some bridges in the database are well over 100 years old, and 23 states exceed the national average of deficient bridges.

Of the approximately 600,000 bridges in the National Bridge Inventory, 280,218 were state-owned in 2010; 302,462 were owned by counties, cities or towns; and 17,316 were owned by other entities, T4 said.

Washington State Department of Transportation

A Washington State Bridge Preservation Office employee inspects the superstructure of the Lewis and Clark Bridge, 340 feet above the Columbia River. WSDOT says it is on track to inspect 1,859 bridges, including 61 underwater, in 2011.

Good News, Bad News

Although some states “have worked hard” to shrink their backlog of deficient bridges, T4 says, the efforts are “not nearly enough.”

In 2009, T4 said, FHWA put the tab at repairing just the nation’s deficient bridges at nearly $71 billion.

“Second, the current level of investment is nowhere near what is needed to keep up with our rapidly growing backlog of aging bridges.”

Top 10 States

Pennsylvania leads—by far—the list of states with the highest percentage of deficient bridges, according to T4. More than one in four of the state’s bridges is considered structurally deficient-5.906 bridges in all, currently carrying nearly 23 million vehicles a day.

Oklahoma ranks second, with 22% of its bridges deficient, but those 5,212 structures carry fewer than 7.5 million vehicles per day. Iowa, Rhode Island and South Dakota round out the top five, with an average of 21.2% deficient bridges—6,727 in all—carrying just over 5.6 million vehicles daily.

On the other end of the spectrum, Nevada has the lowest percentage of deficient bridges (2.2%), followed by Florida (2.4%), Texas (3.0%), Arizona (3.0%) and Utah (4.5%).

What ‘Structurally Deficient’ Means

Federal guidelines classify bridges as “structurally deficient” if one of the three key components—superstructure, substructure or deck—is rated at 4 or less (poor or worse) on a scale of 0 to 9 during inspection. A 4 or less means that engineers have identified a major defect in the support structure or its deck, according to T4.

These individual ratings, as well as other factors, are combined to establish a bridge’s overall “sufficiency rating,” scored 1 to 100. Federal law requires states to inspect all bridges 20 feet or longer at least every two years. Bridges in “very good” condition may go four years between inspections, while those rated “structurally deficient” must be inspected every year, according to T4.

Mapping Tool

T4’s mapping tool includes the whole federal bridge database. Users can enter and see all bridges within a 10-mile radius. Structurally deficient bridges show up as red icons.

Clicking on any bridge will provide more information about it, including its rating.

Report appendices also list the busiest two deficient bridges in each state and their average daily traffic, as well as the 100 Worst U.S. Counties in percentages of deficient bridges.

T4 has also released state reports that include maps of each state, with all counties shaded based on their percentage of structurally deficient bridges.

Transportation for America is a broad coalition of housing, business, environmental, public health, transportation, equitable development, and other organizations. Its more than 500 member groups and partners include the National Association of City Transportation Officials, the National Association of Realtors, National Housing Conference, Natural Resources Defense Council, the Surface Transportation Policy Partnership, and the U.S. Public Interest Research Group.

I just went out to the T4 mapping tool and it doesn't work! Go figure. Sue

Comment from Mary Chollet, (3/31/2011, 9:06 AM)

I've used it a few times and just did again. Did you type in a location?

Comment from Ken Poon, (4/2/2011, 12:02 PM)

As a retired chemist, it is my considered opinion that most structural engineers choose the path of least resistance by virtually doing nothing, other than submitting a report to government agencies.
Based on my experience, there are some economical solutions in the marketplace to address the structurally critical areas such as joints and connections. I believe that if a government agency holds the structural engineers accountable in their field reports, some meaningful action will occur. To their credit, some engineers in the Pacific Northwest take proactive actions while the bridge infrastructure is still salvageable.

Comment from Bill Patterson, (4/5/2011, 5:25 AM)

As a (non-structural) engineer, I question what it is that Ken Poon would have them do? The engineers from either the consulting field or the public sector can make their recommendations, but those recommendations then enter the approval stream. At some level they are filtered by a finance administration before reaching the politicians who make the spending decisions. What "meaningful action" does Mr. Poon envision—-running for office? As for accountability, that is what the engineers' codes of ethics and their professional associations are for. If anyone, engineer or not, considers that an engineer's report does not meet the profession's standards of competency, they have every right to refer it to the association for review.